1. Field of the Invention
This invention concerns a bonding device, with which inadvertent sparking across a cover, which forms a working region, and a torch electrode is prevented.
2. Description of the Related Art
In prior processes with semiconductor devices, wire bonding to mounting parts formed on a lead frame was performed according to each mounting part, and as an embodiment therefor, a bonding device for such wire bonding is disclosed for example in Japanese Unexamined Patent Publication No. Sho-63-29535.
As shown in FIG. 7, a transistor lead frame 2, to which a chip 10 is attached, is set on a heating block part 1. A bonding arm 3 is disposed above lead frame 2 on heating block 1 and a capillary 4 is disposed at the tip of bonding arm 3. A wire 5 is disposed in this capillary 4 and a torch electrode 6, for forming a ball from wire 5, is disposed near capillary 4.
This thermocompression type bonding device is provided with a wire bonding position recognition part 7 and a bonding head driving part 8 as well as with a local heating device 9, which is set to operate in linkage with the operation of bonding head driving part 8 in the X and Y directions and is for heating the bonding part locally. A laser beam device may for example be used as this local heating device 9.
The operations shall now be described. Bonding head driving part 8 is made to move, as programmed in advance in accordance with information from wire bonding position recognition part 7, to lead frame 2 that has been heated by heating block 1, local heating device 9 is made to operate just during the bonding process to perform ball bonding while compensating for inadequate heat on chip 10, capillary 4 is thereafter moved to the lead frame 2 side, local heating device 9 is made to operate again just during the bonding process to perform stitch bonding while compensating for inadequate heat at the lead frame 2 side, and then torch electrode 6 is made to form a ball part at the tip of a wire 5 that has been cut.
Ball bonding is then performed on the other electrode of chip 10 while making local heating device 9 operate just during bonding to compensate for inadequate heat at chip 10, capillary 4 is thereafter moved to the lead frame side, local heating device 9 is made to operate again just during the bonding process to perform stitch bonding while compensating for inadequate heat at the lead frame side, and then torch electrode 6 is made to form a ball part at the tip of a wire 5 that has been cut. Since bonding is thus performed while compensating for inadequate heat at the bonding part, a high quality wire bond is obtained. A wire bond of even higher quality can be obtained by using ultrasonic waves in combination.
Also though the case of a transistor chip was described with the above-described embodiment, this invention is not limited thereto and the chip may be a diode, IC, etc., and the invention can thus be applied as a wire bonder for any semiconductor device.
In the case where mounting parts are formed on a completely punched lead frame 2 as has been described above, just the mounting parts need to be heated, for example, to approximately 250xc2x0 C. during wire bonding. That is, since the entirety of lead frame 2 is not constantly in a high temperature state and wire bonding could be performed by partial heating, problems, such as the oxidation of lead frame 2 did not have to be considered with the bonding device described above.
Though details shall be given with the description of an embodiment of the present invention, in the case where a cluster block, having a plurality of mounting parts within a small area, is formed on a lead frame, etc., the lead frame, etc., will be kept at a high temperature state until all of the wire bonding processes for a single cluster block has been completed. There was thus the problem that a lead frame, etc., with a cluster block becomes oxidized due to being placed in the abovementioned high temperature state over a long period of time. The abovementioned oxidation of lead frame 2, etc., must thus be prevented for example by placing the lead frame in the high temperature state in a space filled with an inert gas, such as nitrogen gas.
In order to form this space, an inert-gas-filled space must be formed above the working base on which the lead frame is set and furthermore, a working hole for recognition and wire bonding must be formed above this space. In this case, the inert gas becomes heated to a high temperature within the space and escapes to the exterior from the working hole due to the ascending air current, and in this process, the peripheral ends of the cover that form the working hole become warped upwards due to the influence of high temperature, etc. As a result, inadvertent sparking occurs across torch electrode 6 and the cover that has warped upwards and prevents the formation of a ball part at the tip of wire 5.
This invention has been made in view of the abovedescribed problem of the prior art, and this invention""s bonding device comprising: a substrate setting base, having a heating function; a cover, which covers a working region from above the abovementioned substrate setting base; a working hole, provided in the upper surface of the abovementioned cover; an illumination, disposed above the abovementioned working hole; a capillary and a torch electrode, disposed at the side face of the abovementioned illumination; and a pattern recognition camera, disposed inside a lens barrel provided above the abovementioned illumination; wherein the abovementioned cover has the periphery of the abovementioned working hole subject to insulation treatment to prevent sparking across the abovementioned torch electrode and the abovementioned cover.
Preferably with this invention""s bonding device, the abovementioned cover has only the periphery of the abovementioned working hole with the side edge closest to the tip of the abovementioned torch electrode subject to insulation treatment.
Also preferably with this invention""s bonding device, insulation treatment of the abovementioned cover is carried out by attachment of a heat-resistant insulating tape.
Also preferably with this invention""s bonding device, the abovementioned heat-resistant insulating tape is tape comprising a fluororesin.
Also preferably with this invention""s bonding device, insulation treatment of the abovementioned cover is carried out by the forming of an insulating layer comprising a fluororesin.
Also preferably with this invention""s bonding device, insulation treatment of the abovementioned cover is carried out by adhesion of an insulating plate.
Also preferably with this invention""s bonding device, the abovementioned insulating plate is a ceramic plate.
Also preferably with this invention""s bonding device, the side that is punched in the process of forming the abovementioned working hole is positioned at the rear side of the abovementioned cover.
Also in order to solve the above-described problem this invention provides a bonding device comprising: a substrate setting base, having a heating function; a cover, which covers a working region from above the abovementioned substrate setting base; a working hole, provided in the upper surface of the abovementioned cover; an illumination, disposed above the abovementioned working hole; a capillary and a torch electrode, disposed at the side face of the abovementioned illumination; and a pattern recognition camera, disposed inside a lens barrel provided above the abovementioned illumination; wherein the abovementioned cover is arranged by covering the upper surface of a damper with a conductive plate and the abovementioned conductive plate has the periphery of the abovementioned working hole, provided in the abovementioned conductive plate, subject to insulation treatment to prevent sparking across the abovementioned torch electrode and the abovementioned conductive plate.
Also preferably with this invention""s bonding device and circuit device manufacturing method, the abovementioned conductive plate is made from stainless steel.
This invention""s bonding device is characterized in that with the conductive plate, which makes up the cover that covers the working region above the above-described substrate setting base, insulation treatment is applied to the periphery of the working hole in the conductive plate. Inadvertent sparking across the above-described conductive plate and the torch electrode, which is caused by upward warping of the conductive plate at the periphery of the above-described working hole, can thus be prevented. A bonding device can thus be realized with which inadvertent sparking can be prevented without obstructing the merits of prevention of oxidation of the surface of a lead frame within the abovementioned working region, improvement of the bonding speed by the moving of the abovementioned working hole, etc.
This invention""s bonding device is also characterized in that the side, which is punched in the process of forming the abovementioned working hole in the abovementioned conductive plate, is positioned at the inner surface side of the abovementioned working region. The conductive plate at the periphery of the abovementioned working hole thus warps upward above the abovementioned working region. As a result, the abovementioned working region will not be invaded by the conductive plate at the periphery of the abovementioned working hole, and a bonding device can be realized with which there are no problems of bending of a thin metal wire within the abovementioned working region due to the conductive plate at the periphery of the abovementioned working hole.